Figure 1.9 - Circuit Board Test Points.................................................. 1

rate value (refer to Figure 1.5). For each analog input cycle, the A/D (Analog-to-Digital) converter reading is added to the offset value. The rate of change of the resulting sum is limited by the slew rate value. This limited result is sign extended to a 32-bit value and made available to the Macroprogram. The analog output channel provides a ±10 VDC output channel with its common referenced to controller ground. Under Macroprogram control, the user may select an analog offset value and a maximum slew rate for the analog output channel (refer to Figure 1.5). For each analog output cycle, the analog output value specified in the Macroprogram is added to the analog offset value and the slew rate limit applied. The resulting value is output to the D/A (Digital-to-Analog) converter.

A pair of voltage reference signals are available for connection to a potentiometer. Each reference provides nominally +10 VDC and -10 VDC and each can deliver up to 10 mA of current.

1.2.3 INPUT/OUTPUT MODULES

The MSC-250 controller has 16 on-board locations for I/O (Input/Output) modules (refer to Figure 1.6). In addition, two IOE-850 I/O Expanders of 16 positions each can be daisychained from the INPUT/OUTPUT EXPANDER PORT to provide an additional 32 I/O locations. Any of the 48 positions can be used for either an AC or DC input or output module.

When equipped with an input module, the controller will monitor the location for a specific change in state of the module, as directed by the Macroprogram, and will perform specific actions when the state change occurs. When equipped with an output module, the

Figure 1.5 - Analog Input and Output Channel Block Diagrams